One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,7)(4,6)(5,8)(9,10,13,16)(11,17,19,24)(12,20,22,15)(14,21,23,18)(25,26,30,33)(27,31,36,38)(28,32,29,34)(35,40,37,39)(1,3,4,8)(2,5,6,7)(25,27,29,37,30,36,28,35)(26,31,34,39,33,38,32,40)(9,11,13,19)(10,14,16,23)(12,21,22,18)(15,24,20,17)(26,32)(27,35)(28,29)(31,38)(33,34)(36,37)(2,6)(5,7)(26,33)(27,36)(32,34)(35,37) involution — undirectedA Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.